If you own property in a coastal city, coastal flood safety is worth knowing — whether your house sits on the beach or ten minutes inland, and whether or not there's a hurricane anywhere near you.

It doesn't just take a tropical system or nor'easter to cause flooding near you. A routine high tide on a clear day or heavy rain that simply has nowhere to drain can still pack a punch.

Different causes, same water, same risk to your property. And beyond the flooding itself, there's erosion quietly reshaping your flood zone and insurance gaps that only show up after the damage is done.

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Know your surge zone

When forecasters say storm surge could reach "X feet above ground level," that number is measured against normal high tide — not your elevation, and not how far you feel like you live from the ocean.

A 6-foot surge doesn't stop at the boardwalk. It travels up rivers, canals and storm drains into neighborhoods that don't think of themselves as "coastal" at all.

It matters for insurance too: standard homeowners policies don't cover storm surge. That requires separate flood insurance, based on your official flood zone.

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What the alerts actually mean

Coastal flood alerts aren't the same as the inland flood watches you already know — and the difference is what turns a forecast into action.

• Coastal flood advisory: Minor coastal flooding is occurring, enough to flood low-lying roads and properties near the coast. Use caution in affected areas.
• Coastal flood watch: Moderate to major coastal flooding is possible and could pose a serious risk to life and property. If you live or work in a coastal flood-prone area, now is the time to prepare and know your evacuation options.
• Coastal flood warning: Moderate to major coastal flooding is occurring and poses a serious threat to life and property. Follow evacuation orders immediately and stay out of flooded areas.

(MORE: Weather alerts decoded: What advisories, watches and warnings really mean)

When it floods with no storm in sight

Not every coastal flood needs a storm. "Sunny-day" flooding happens when a routine high tide — often a seasonal "king tide" — simply runs higher than the streets can handle, pushing water into roads and yards on an otherwise clear day.

(MORE: What are king tides?)

It's happening more often in a lot of coastal cities, and because there's no storm attached, it catches people off guard.

If your street floods on the highest tides of the month even when the sky is blue, that's not a fluke — it's a sign you're in an active tidal flood zone, worth confirming with your local floodplain office.

Watch the dunes, not just the forecast

Erosion is reshaping flood risk for entire coastal cities, not just the properties losing sand. As dunes and barrier islands wear down, they lose their ability to buffer the city behind them — meaning neighborhoods and downtowns set back from the shoreline lose natural protection too.

(MORE: What is coastal erosion?)

That erosion is also quietly redrawing FEMA flood zone maps well inland of the beach itself. A property that wasn't in a mandatory flood insurance zone five years ago can be in one now — meaning a lender suddenly requires coverage you didn't have, or your premium jumps at renewal with little warning.

Check your coverage before the water rises

Saltwater does more damage than freshwater flooding — corroding wiring, HVAC systems, vehicles — and that's not limited to beachfront property. Any home connected to tidal waterways, surge channels or brackish groundwater can be exposed.

Standard flood insurance often has gaps around erosion and slow-onset tidal flooding too. Call your insurance provider and ask, in plain terms, what's covered — before hurricane season, before nor'easter season, before the next high tide. Not during it.

Faiza Mohammed is a meteorologist intern at weather.com. She studied geography and worked with the Weather Dawgs team at the University of Georgia. She also received her master's in Earth and Atmospheric Sciences from the Georgia Institute of Technology.